Essential components:

  • Self-inflating bag
    In various sizes:
    • Infant: 240mL
    • Child: 500mL
    • Adult: 1600mL
  • Oxygen source
  • Air inlet valve
    Draws room air into the bag if the oxygen reservoir is empty and the bag is still inflating.
  • One-way valves
    Sit between the self-inflating bag and the:
    • Gas source
      Refill valve prevents reflux of gas into the reservoir instead of into the patient.
    • Exhalation port Non-rebreathing valve prevents expiration into the self-inflating bag, and forces expiration through the exhalation port (or PEEP valve, if present).
  • 15mm adaptor
    For mask or airway device.
  • High pressure relief valve
    Pop-off valve prevents Pip rising excessively (usually at ~40-65cmH2O, depending on model).

Optional components:

  • PEEP valve
    Partially occludes exhalation port to provide PEEP. May be built-in or sold separately.
  • Oxygen reservoir
    Must be at least as large as the bag. Allows buffering of gas flow into the self-inflating bag (as peak flow will be less than that supplied from the oxygen source), and allows 100% O2 to be delivered provided the minute ventilation is less the O2 flow rate.



  • Attach to supplemental oxygen
  • Attach to mask or airway device
  • Hand ventilate



  • Cheap
  • Effective
  • Widely available
  • Portable
  • Requires no power


  • Can deliver close to 100% oxygen
  • Minimal dead space
  • Pop-off valve reduces risk of barotrauma
  • Highly compatible
    15mm adaptor compatible with masks, LMA, ETT, and other in-line airway add-ons (ETCO2, bronchoscopic Y-piece, etc.).



  • Misassembly Reusable BVM systems can occasionally have their valves inserted backwards, giving risk of barotrauma and failure of oxygen delivery.


  • Less effective for spontaneous ventilation
    • Delivered FiO2 may vary substantially between devices
    • Requires sufficient ventilatory effort to open one-way valves
      Failure will result in air entrainment rather than oxygen.
  • Lower FiO2 delivered at high MV
  • Bulky
  • Easy to hyperventilate
  • Unable to gauge lung compliance
    Risk of barotrauma.
  • Difficulty assessing delivered tidal volumes

Last updated 2021-08-23

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